Multistage centrifugal pump



May 17, 1927;

A. HOLLANDER MULTIS TAGE CENTRIFUGAL PUMP Filed June 2 192's ZSheets-Sheet 1 Jiaveni or,

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. 1,628,84T I May 1927' A. HOLLANDER MULTIS'I-AGE CENTRIFUGAL PUMP Filed June 2 1926 2 Sheets-Sheet 2 Inven t or.

Patented May 17, 1927.

UNITED STATES,

ALADAB HOLLANDER, OF BERKELEY, CALIFORNIA, ASSIGNOR TO BYRON JACKSON I PATENT OFFICE.

PUMP MFG. 00., OFBEBKELEY, CALIFORNIA, A CORPORATION OF CALIFORNIA.

MULTISTAGE CENTRIFUGAL PUMP.

Application filed June 2, 1926. Serial No. 118,171.

My invention has for its object a multistage centrifugal pump with the stages arranged in pairs and having thevarious compartments of different pressures arranged in such a way as to maintain the most perfect balance between the various leakages and thrust pressures, combined in a simple mechanical construction accomplishing a facility and security of operation.

A further object is a pump of the character described which may be readily operated with a minimum number of changes under a plurality of pressure and volume deliveries.

These objects I attain by mounting a plurality of pairs of impellers on a single shaft, the two impellers of each pair a apted to receive their suction supply from opposite directions whereby they are substantially balanced and in addition, the pairs of impellers representing the lower stage of pressures are located at one end of said group and the pair of impellers representing the next higher stage are located at the other end of said group, whereas other pairs of impellers representing the still higher stages are located intermediate thereto.

The packing glands on each end of the casing are therefore under minimum pressures.

In the pump of my construction I also prefer to arrange the upper halves of the casings in one or more castings and the lower halves of the casin in another casting or castings, whereby a orizontal joint or parting is provided in the plane of the shaft axis, with holding bolts between the upper and lower casing portions and arranged about the periphery of the various pressure compartments.

The construction herein specified results in the suction compartments of adjacent pairs being adjacent each other and also in a minimum pressure difference between the several adjacent suction compartments, thus resulting in a minimum of leakage. I

Moreover, by arranging the stages in the order of 1, 2, 8, 7, 5, 6, 4, 3, or 1, 2, 7, 8, 6, 5, 4, 3, the leakages between any two pairs of runners will not disturb the balance of the entire unit, as the force produced by the variations of pressure leakage, acting against an impeller of the higher stage of any pair, is counteracted by an increase of pressure against the impeller of the lower stage of the same pair.

In an eight stage pump emplo', my invention, by suitable connections, is e unit may be employed with the impellers all in series thus securing an eight stage pump, or it may be employed in two groups of four operating in parallel, thus securing an increased elivery at the reduced pressure.

By referring to the drawing and specifications my invention will be made more clear.

In the drawing: Fig. 1 is a plan artly in view and partly 1n section of an eig t stage centrifugal pump employing my invention.

Fig. 2 is a cross section on the line II-II of Fig. 1.

Fig. 3 is a diagrammatic showing of the several stages and volute paths therebetween, when all eight impellers are employed in series.

Fig. 4 is similar to Fig. 3 when the ump is employed with two groups in paralle each group having four impellers in series.

Throughout the figures similar numerals refer to identical parts.

The numeral 1 indicates a lower casting forming the lower half of the casings for all eight impellers, while 2 indicates generally the upper half of the casings.

A main driving shaft is shown at 3 on which aremounted four pair of impellers 4, 5 6, 7, 8, 9 10, 11 respectively.

Shaft glan are shown at 12, 13 and each of the impellers is provided with a volute 'or pressure chamber which chambers are shown at 14, 15, 16, 17, 18, 19, 20, 21 respectively, and with suction chambers 22, 23, 24, 25, 26, 27 28, and 29 respectively.

Conduits between the volute chambers and the suction of the next higher sta e are shown from volute 14 to suction 23 y the dotted lines at 30, 30; from volute 17 to 22 is shown at 36; a pipe connection to volute 16 at 37; a pipe connection to suction chamber 26 at 38; afpipe connection from volute 20 at 39.

A main suction supply is shown at 40,

branching to the connection 36, and the other branch passing the check or one way valve 41 and thence into a T pipe at 42.

One branch of this T is connected to the inlet 38 by the branch 43 and to a main gate valve 45 y the branch 44.

From the other side of the main gate valve 45 extends the branch 46 of a T having branches 47 connecting with the pipes 39 and 48 connecting through the one way valve 49 with a delivery branch 50.

The volute discharge 37 is conveyed through the pipe 51 and combined with the discharge from the pipe 50 in the single discharge pipe 52 as diagrammatically shown in Fig. 4. a

If the gate valve 45 be closed the pump will operate as two parallel groups of two pairs each or four impellers, fluid being supplied initially to impellers 4 and 8 through the suction inlet 40 and pipe 36 and also through the one way valve 41 and pipes 43, 38. See Fig. 4.

Pressure discharge will be delivered from outl'e'ts 37 and 39 after having been raised through the four stages in each group corresponding with impellers 4, 5. 11, 10 and 8, 9, 7, 6, respectively in the order named.

Thedelivery pressure from pipe 37 passes on through the pipe 51 and thence into the common discharge pipe 52, and from the pipes 39, 47 and 48, the check or one way valve 49, pipe 50 and into the common discharge 52.

The pump is now operating at less pressure and increased capacity over that when it is employed with all of the groups in series as shown in Fig. 3.

To operate under higher pressure and less capacity with all the groups in series the valve 45 is opened. This admits pressure from the higher stage, 46 through the valve 45 and into branch 44 of the T pipe. The pressure is therefore higher on the right side of the one way valve 41 and this valve will close, the pressure now being supplied through the valve 45 and T branches 44, 43 and inlet pipe 38 and which supply has already been raised in pressure through the four stages corresponding in order with impellers 4, 5, 11, 10, and is now admitted through the inlet chamber 26 and impeller 8 and is then raised through the additional stages corresponding with impellers 8, 9, 7 6, consecutively and discharged from the latter through the delivery pipe 51 having been raised through all eight stages.

This from discharge 52 produces a back pressure at 50 in excess of that at'48 and the one way valve 49 will therefore be closed and retained u on its seat.

The disc large pressure at 52 is now a maximum the eight impellers operating in series.

Particular attention is directed to the hydraulic balance attained in this unit at all times. The placing of the runners back to back balances, the pressure from one inlet against the other inlet of each pair. here impellers are made ri ht and left and physically similar, the difi brences in leakages in diiferent parts of the mechanism establish differences of pressure and bring about a thrust in one direction or the other; and these I employ to counterbalance each other as follows.

Referring to Fig. 1, such fluid as leaks between the shaft 3 and collar 60 will pass from the volute of higher pressure 15 towards the impeller 4, thus occasioning an increment of thrust to the left. At the other end of the shaft the leakage will be in the opposite direction, to-wit from the volute 20 towards runner 11 occasioning a thrust pressure to the right and counterbalancing that mentioned above as against runner 4.

These two pairs will therefore counterbalance each other.

In the same way the resulting thrust between runners 6, 7 will be to the ri ht and that between runners 8, 9 to the left again (-ountcrbalacing each other. The pressure occasioned by these leakages between each pair of the members will therefore be counterbalanced by the other pair of the same group.

()ther pressure differences will occur being ouasioned by leakages between the shaft and sleeves as at 61.

The shaft is here made of a relatively close running lit but under the high pressure handled by the pump the pressure resulting from the leakages becomes material. The difference in pressures between suction 23 and suction 24 will be that between the first stage and the seventh stage, that is corresponding with six stages and its direction will be toward the left.

That between suctions and 26 will be the difference between the sixth stage and the fourth stage, that is two stages and its direction will be towards the right.

That between suctions 27 and 28 will be the difi'erence between the third stage and the fifth stage, that is two stages and its direction will be towards the right.

The pressure increment in each of these cases will be as the square root of the head corresponding with the stage, and as the stages are equal we therefore have the square root of six acting at the left, counterbalanced by twice the square root of two acting to the right, that is 2.55 as against 2.83 or a total unbalanced pressure of only .28 times the pressure created by one single stage, an amount which is negligible in ordinary commercial operation and easy to take care of with any conventional means without a material drop in efiiciency.

The arrangement of the stages is here shown in the order of 1, 2, 8, 7, 5, 6, 4, 3, when all the stages are in series, that is runner 4 establishes the first stage, runner 5 the second stage, runner 11 the third stage, runner 10 the fourth stage, runner 8 the fifth stage, runner 9 the sixth stage, runner 7 the seventh stage and runner 6 the eighth stage.

WVhen operating in parallel, runners 4 and 8 in parallel form the first stage, runners 5 and 9 in parallel the second stage, runners 11 and 7 in parallel the third stage and runners 6 and 10 in parallel the fourth stage.

It will of course be understood that the flow through the impellers and volutes is always in the same direction whether the pump be operating in series or in parallel whereas the flow of water through the pipe connections external to the pump proper will be different through the T pipes.

The direction arrows of Fig. 1 correspond with the flow in the pipe connections when the gate valve is closed and the two groups of impellers are operating in parallel.

In the pump'of my construction I prefer to form the several volute chambers in a main casting formed of two parts having the plane flange joint in the horizontal plane of the shaft axis as shown at 70, see Fig. 2.

I claim: i i

1. In a multi-stage centrifugal pump a group comprising a plurality of pairs of similar impellers, the impellers of each pair mounted back to back with their discharge compartments adjacent and their suction compartments remote, the pair of impellers representing the lowest stage being located at one end of said group, and the pair of impellers representing-the next higher stage, located at the other end of said group, and impellers of the highest stage intermediate said end positioned pairs, all of said impellers fixed on a shaft and inclosed within a casing and fluid ducts between the discharge compartment of each impeller and the suction compartment of the impeller of the next higher stage in combination with pipe connections comprising a suction pipe adapted tosupply fluid to be pumped to the suction compartment of the first stage, a one way valve and a branch adapted to supply fluid to be pumped to the suction inlet of an intermediate stage, a delivery pipe adapted to receive pumped fluid from the highest stage, a branch adapted to receive pumped fluid from another intermediate stage and a one way valve between said branch and said delivery pipe and a main gate interposed between said branches.

2. In a multistage centrifugal pump 8 impellers mounted on the same shaft, a volute and a suction for each impeller and identified as 1 to 8 inclusive and consecutively, fluid conduits from volute l to suction 2, also from volute 2 to suction 8, also from volute 8 to suction 7, also from volute 7 to suction 5, also from volute 5 to suction 6, and from volute 6 to suction 4, also from volute 4 to suction 3, a suction connection to impeller 1 and a discharge connection from volute 3.

3. In a multistage centrifugal pump 8 impellers mounted on the same shaft, a volute and a suction for each impeller and identified as 1 to 8 inclusive and consecutively, fluid conduits from volute 1 to suction 2, also from volute 2 to suction 8, also from volute 8 to suction 7, also from volute 7 to suction 5, also from volute 5 to suction 6, and from volute 6 to suction 4, also from volute 4 to suction 3, a suction connection to impeller 1 and having a branch connection to suction 5 and a discharge connection from volute 3, and a discharge connection from volute 7 connected therewith and valve means in each of said branches.

ALADAR HOLLANDER. 

